Analog Devices Inc. LT1168ACS8#TRPBF

Overview

LT1168ACS8#TRPBF from Analog Devices (acquired Linear Technology) is a micropower, precision instrumentation amplifier requiring only one external resistor to set gains from 1 to 10,000. It delivers 10nV/√Hz input voltage noise at 1kHz, 40µV max input offset voltage, and 90dB CMRR at G=1 while operating from ±2.3V to ±18V supplies with just 530µA max supply current - ideal for high-accuracy bridge sensor conditioning in portable medical or industrial data acquisition systems.

For engineers reviewing the LT1168ACS8#TRPBF datasheet, LT1168ACS8#TRPBF pinout, LT1168ACS8#TRPBF application, or LT1168ACS8#TRPBF equivalent, this page provides verified pin functions, gain-programming design meaning, ESD-robust operation up to 13kV HBM, IEC 1000-4-2 Level 4 compliance with two 5kΩ resistors, and validated alternatives for strain gauge, thermocouple, and differential-to-single-ended conversion use cases.

Technical Context

The LT1168ACS8#TRPBF implements a laser-trimmed, three-op-amp instrumentation architecture with superbeta NPN input transistors enabling 250pA max input bias current and 0.3µV/°C max input offset drift. Its gain equation G = 1 + (49.4kΩ/RG) is realized via matched internal 24.7kΩ resistors (R1/R2), ensuring <0.4% gain error at G=10 and 20ppm nonlinearity under 2kΩ load conditions.

Unlike legacy monolithic instrumentation amps, it maintains specified nonlinearity down to 2kΩ loads and supports capacitive loads up to 1000pF across all gains without instability. Input common-mode range extends to –VS + 1.9V and +VS – 1.4V (at G=1), and reference terminal (Pin 5) requires minimal series resistance to preserve >90dB CMRR and avoid gain error degradation.

Key Specifications

Pinout & Package

LT1168ACS8#TRPBF is housed in an 8-pin SOIC (S8) package with 1.27mm pitch, JEDEC MS-012AC compliant, and rated for 190°C/W junction-to-ambient thermal resistance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar instrumentation amplifier applications.

Compared with AD8421ARMZ and INA128UA, the LT1168ACS8#TRPBF uniquely balances micropower operation (530µA), ultra-low offset (40µV), and certified ESD/EMC robustness - making it the only choice for portable, battery-powered precision sensor interfaces requiring zero external protection components.

Availability

LT1168ACS8#TRPBF is available at Aetrix Electronics and suitable for bridge amplifiers, strain gauge conditioners, and thermocouple interfaces requiring stable component supply, long-term lifecycle support, and guaranteed traceability for medical and industrial OEM programs.

Supply support for LT1168ACS8#TRPBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.

The LT1168 product line was originally developed by Linear Technology (acquired by ADI in 2017) to address demand for low-power, high-accuracy instrumentation amplifiers in portable and harsh-environment measurement systems.

FAQ

What is the maximum gain achievable with LT1168ACS8#TRPBF and how is it set?

The LT1168ACS8#TRPBF supports gains from 1 to 10,000, set by a single external resistor RG connected between Pins 1 and 8 using the formula G = 1 + (49.4kΩ/RG). For G=10,000, RG = 4.94Ω; for G=1, RG is left open. The LT1168ACS8#TRPBF datasheet specifies performance across this full range, including 0.5% max gain error at G=1000 and 20ppm nonlinearity at G=10 with 2kΩ load.

Does LT1168ACS8#TRPBF support single-supply operation?

Yes, the LT1168ACS8#TRPBF operates from single supplies as low as +4.6V (±2.3V equivalent) with appropriate reference biasing. For reliable single-supply use, the REF pin (Pin 5) must be raised above the negative rail (e.g., to mid-supply), and at least one input must remain ≥2.5V above ground. The LT1168ACS8#TRPBF input common-mode range extends to –VS + 1.9V and +VS – 1.4V at G=1, enabling rail-to-rail-compatible sensing in 3.3V or 5V systems with proper level-shifting.

What is the purpose of the REF pin on LT1168ACS8#TRPBF and how should it be used?

The REF pin (Pin 5) on the LT1168ACS8#TRPBF defines the output voltage reference point - the OUTPUT (Pin 6) voltage is always measured relative to REF. To maintain >90dB CMRR and avoid gain error, series resistance to REF must be <6Ω; even 6Ω degrades CMRR to 80dB and adds 0.02% gain error. For buffered referencing, a low-output-impedance op amp (e.g., half of LT1112) should drive REF directly, as shown in Figure 4 of the LT1168ACS8#TRPBF datasheet.

How does LT1168ACS8#TRPBF handle capacitive loads and what is the maximum stable value?

The LT1168ACS8#TRPBF is internally compensated to remain stable with capacitive loads up to 1000pF across all gain configurations (G=1 to 10,000). This eliminates the need for external isolation resistors in ADC driver applications. Stability is verified per Figure 16 in the LT1168ACS8#TRPBF datasheet, which shows <10% overshoot with 1000pF load at G=1, G=10, and G=100. For loads >1000pF, a series 10Ω–22Ω resistor at the output restores stability without affecting DC accuracy.

Is LT1168ACS8#TRPBF pin-compatible with AD620 or INA118?

Yes, the LT1168ACS8#TRPBF is explicitly designed as a pin-for-pin improved second source for both AD620 and INA118, sharing identical 8-pin SOIC (S8) and PDIP footprints. It improves upon them with lower supply current (530µA vs 1.3mA), lower input offset (40µV vs 50µV), better CMRR (90dB vs 80dB at G=1), and integrated 13kV HBM ESD protection - all without requiring PCB layout changes or schematic modifications when replacing either part.